Isolation Barrier

ABSTRACT

An apparatus and method for securing a tubular within another tubular or borehole, creating a seal across an annulus in a well bore, and centralising or anchoring tubing within a wellbore. A sleeve is arranged on a tubular body to create a chamber therebetween. A port provides fluid access through the body to the chamber. A torsion spring is located within the chamber. When fluid is introduced into the chamber the sleeve is morphed to secure it to a well bore wall and the torsion spring unwinds to a relaxed state. The relaxed torsion spring supports the morphed sleeve against collapse.

The present invention relates to an apparatus and method for securing atubular within another tubular or borehole, creating a seal across anannulus in a well bore, and centralising or anchoring tubing within awellbore. In particular, though not exclusively, the invention relatesto morphing a sleeve to secure it to a well bore wall by the use offluid pressure and providing a torsion spring to support of the sleevein the event of collapse so as to maintain a seal between the sleeve andwell bore wall.

In the exploration and production of oil and gas wells, packers aretypically used to isolate one section of a downhole annulus from anothersection of the downhole annulus. The annulus may be between tubularmembers, such as a liner, mandrel, production tubing and casing orbetween a tubular member, typically casing, and the wall of an openborehole. These packers are carried into the well on tubing and at thedesired location, elastomeric seals are urged radially outwards orelastomeric bladders are inflated to cross the annulus and create a sealwith the outer generally cylindrical structure i.e. another tubularmember or the borehole wall. These elastomers have disadvantages,particularly when chemical injection techniques are used.

As a result, metal seals have been developed, where a tubular metalmember is run in the well and at the desired location, an expander toolis run through the member. The expander tool typically has a forwardcone with a body whose diameter is sized to the generally cylindricalstructure so that the metal member is expanded to contact and sealagainst the cylindrical structure. These so-called expanded sleeves havean internal surface which, when expanded, is cylindrical and matches theprofile of the expander tool. These sleeves work well in creating anannular seal between tubular members but can have problems in sealingagainst the irregular surface of an open borehole.

The present applicants have developed a technology where a metal sleeveis forced radially outwardly by the use of fluid pressure actingdirectly on the sleeve. Sufficient hydraulic fluid pressure is appliedto move the sleeve radially outwards and cause the sleeve to morphitself onto the generally cylindrical structure. The sleeve undergoesplastic deformation and, if morphed to a generally cylindrical metalstructure, the metal structure will undergo elastic deformation toexpand by a small percentage as contact is made. When the pressure isreleased the metal structure returns to its original dimensions and willcreate a seal against the plastically deformed sleeve. During themorphing process, both the inner and outer surfaces of the sleeve willtake up the shape of the surface of the wall of the cylindricalstructure. This morphed isolation barrier is therefore ideally suitedfor creating a seal against an irregular borehole wall.

Such a morphed isolation barrier is disclosed in U.S. Pat. No.7,306,033, which is incorporated herein by reference. An application ofthe morphed isolation barrier for FRAC operations is disclosed inUS2012/0125619, which is incorporated herein by reference. Typically,the sleeve is mounted around a supporting tubular body, being sealed ateach end of the sleeve to create a chamber between the inner surface ofthe sleeve and the outer surface of the body. A port is arranged throughthe body so that fluid can be pumped into the chamber from thethroughbore of the body.

US2007/0089886 to Schlumberger Technology Corporation discloses anexpandable sleeve for use in a well, comprising a tubular structureincluding an external sealing layer comprising a compliant material; anintermediate expandable tubular body made from a plastically deformablematerial; and an internal spring structure such as a helically woundspring; wherein the external sealing layer is disposed on the outersurface of the tubular body, and the internal spring structure isdisposed inside the tubular body and acts so as to exert a radial forceon the body when in an expanded state. The sleeve is expanded by runninga cone through the tubular. In use, the spring must be held incompression when the tubular structure is run-in a well bore andreleased when the radial support is required following expansion.Alternatively, the tubular body is located in the well bore and expandedprior to the spring being run-in and inserted in the expanded to body toprovide radial support. A disadvantage of this arrangement is that eachof the processes requires a second trip into the well bore to releasethe spring or locate the spring in position.

GB2417271 to Schlumberger Holdings Limited describes an energisedsealing element for a packer that maintains a seal under variousconditions by providing a source of stored energy that can be used toinsure that contact forces are maintained between the seal and the wallor casing of the wellbore. Various combinations of sealing layers,support sleeves and energising elements are disclosed. The seal layermay be made from rubber, an elastomeric compound, metal, thermoplasticor other soft, deformable materials. The support sleeve and energizingelement may be made of metal, composite materials or various othermaterials that would permit the storage of mechanical potential energy.The energising element may take the form of a bow and wedges, a spring,a bag or container which is energised with gas or other compressiblematerial or a swelling material. For the spring arrangement, a coil typespring is described held in place by a pin or weld. Such an arrangementrequires a mechanism to release the spring when the packer is in thedesired position. For the bow arrangement, wedges are moved radiallyinside the bow to force the bow radially outwards to contact and movethe support sleeve. Again a mechanism is required to move wedges insidethe bow when the packer is to be expanded. Such additional mechanismsmay fail, thus preventing expansion of the packer.

A further disadvantage of the prior art spring arrangements is that thespring is left exposed within the throughbore of thebarrier/packer/sleeve following expansion. This provides multiple pointsfor the build-up of debris or for later run tools to catch and stickupon.

It is therefore an object of at least one embodiment of the presentinvention to provide a morphed isolation barrier which obviates ormitigates one or more disadvantages of the prior art.

It is a further object of at least one embodiment of the presentinvention to provide a method of creating an isolation barrier in a wellbore which obviates or mitigates one or more disadvantages of the priorart.

According to a first aspect of the present invention there is providedan assembly, comprising:

a tubular body arranged to be run in and secured within a largerdiameter generally cylindrical structure;a sleeve member positioned on the exterior of the tubular body, tocreate a chamber therebetween;the tubular body including a port to permit the flow of fluid into thechamber to cause the sleeve member to move outwardly and morph againstan inner surface of the larger diameter structure; andcharacterised in that:at least one torsion spring is located within the chamber;the torsion spring relaxing as the sleeve member is moved outwardly byfluid pressure to provide a frame within the chamber when the sleevemember is morphed against the inner surface of the larger diameterstructure.

In this way, the torsion spring is always contained within a chamber andis advantageously activated by the fluid pressure used to morph thesleeve member. Thus a second run in the well-bore is not required toposition/operate the spring and the spring is not left exposed in thethroughbore. The relaxed torsion spring creates a frame to support thesleeve member and assist in preventing collapse, once the sleeve hasbeen morphed by fluid pressure.

Preferably, the torsion spring is a helically coiled spring whichunwinds as it relaxes. In this way, the torsion spring can be helicallywound around the tubular body to ease construction.

Preferably, the torsion spring has a relaxed diameter less than thediameter of the larger diameter structure. More preferably, the torsionspring has a relaxed diameter less than the diameter of the morphedsleeve. In this way, the torsion spring provides a frame with a diameterless than the diameter of the larger diameter structure and, preferably,less than the diameter of the morphed sleeve. Also, the torsion springdoes not exert a radial force on the morphed sleeve. This is in contrastto the prior art spring arrangements and advantageously prevents ruptureof the sleeve when it is thinned during expansion.

Preferably, the torsion spring has a square or rectangularcross-section. In this way, the torsion spring presents a flat, smoothsurface to contact the inner surface of the sleeve member. This limitsdamage or puncturing of the sleeve member as it is thinned duringmorphing.

The sleeve member may have a first end which is affixed and sealed tothe tubular body and a second end which includes a sliding seal topermit longitudinal movement of the second end over the tubular body. Inthis way, as the sleeve is morphed, longitudinal contraction of thesleeve member occurs which reduces the thinning of the sleeve memberduring morphing.

The large diameter structure may be an open hole borehole, a boreholelined with a casing or liner string which may be cemented in placedownhole, or may be a pipeline within which another smaller diametertubular section requires to be secured or centralised.

The tubular body is preferably located coaxially within the sleeve andis part of a tubular string used within a wellbore, run into an open orcased oil, gas or water well. Therefore the present invention allows acasing section or liner to be centralised within a borehole or anotherdownhole underground or above ground pipe by provision of a morphablesleeve member positioned around the casing or liner. Centralisationoccurs as the sleeve will expand radially outwardly at a uniform ratewith the application of pressure from the fluid. Additionally, thepresent invention can be used to isolate one section of the downholeannulus from another section of the downhole annulus and thus can alsobe used to isolate one or more sections of downhole annulus from theproduction conduit.

Preferably, there is a plurality of ports arranged through the tubularbody. In this way, rapid morphing of the sleeve member can be achieved.The ports may be arranged circumferentially around the body. The portsmay be arranged longitudinally along the body. As the torsion spring iscoiled helically around the tubular body, space may be left between eachadjacent coil so that fluid can bypass the springs at all times to actagainst the sleeve member. This is in contrast to the prior artarrangements of a tube in which slots are cut longitudinally orhelically on the tube body. Fluid flow through the wall of the tube isrestricted until sufficient longitudinal compression of the tube hasoccurred to move the strips, between the slots, radially outwards.

The port may include a barrier. In this way, fluid is prevented fromentering the chamber until activation is required. The barrier may be arupture disc which allows fluid to flow through the port at apredetermined fluid pressure. Alternatively the barrier may be a valve.Preferably the valve is a one-way check valve. In this way, fluid isprevented from exiting the chamber. More preferably the valve is set toclose when the pressure in the chamber reaches a morphed pressure value.In this way, the torsion spring can assist in morphing the sleeve byexerting a radial force on the sleeve member during morphing, but willnot exert any pressure at the time the seal is made between the sleevemember and the larger diameter structure.

According to a second aspect of the present invention there is provideda method of setting a morphed sleeve in a well bore, comprising thesteps:

-   (a) locating a sleeve member on the exterior of a tubular body and    sealing it thereto to create a chamber therebetween,-   (b) locating a torsion spring in the chamber;-   (c) running the tubular body on a tubular member into a wellbore and    positioning the sleeve member at a desired location within a larger    diameter structure;-   (d) pumping fluid through the tubular member and through a port in    the tubular body to access the chamber;-   (e) causing the sleeve member to move radially outwardly and morph    against an inner surface of the larger diameter structure;-   (f) allowing the torsion spring to relax and exert a radial force on    the sleeve member as the sleeve member is moved radially outwardly    towards the inner surface of the larger diameter structure; and-   (g) creating a frame from the relaxed torsion spring to prevent    collapse of the morphed sleeve member.

In this way, the naturally occurring unwinding of the torsion springduring morphing is used to assist in expanding the sleeve member andonce relaxed, the torsion spring acts as a frame to support the morphedsleeve and prevent collapse thereof. Thus the creation of the barrierand the frame, formed from the relaxed spring, can be achieved in asingle run in the well bore.

Preferably, the method includes the step of selecting a torsion springhaving a relaxed diameter less than a diameter of the larger diameterstructure. More preferably, the method includes the step of selecting atorsion spring having a relaxed diameter less than a calculated diameterof the morphed sleeve.

The large diameter structure may be an open hole borehole, a boreholelined with a casing or liner string which may be cemented in placedownhole, or may be a pipeline within which another smaller diametertubular section requires to be secured or centralised.

Preferably, step (d) includes the step of pumping fluid through thetubular member and through multiple ports in the tubular body to accessthe chamber. This provides a faster morphing of the sleeve.

Preferably, the method includes the step of rupturing a disc at a valvein the port to allow fluid to enter the chamber when the pressurereaches a desired value. This allows selective and controlled activationof the morphing process.

The method may include the steps of running in an activation fluiddelivery tool, creating a temporary seal above and below the port andinjecting fluid from the tool into the chamber via the port. Such anarrangement allows selective operation of the sleeve member if more thanone sleeve member is arranged in the well bore.

In the description that follows, the drawings are not necessarily toscale. Certain features of the invention may be shown exaggerated inscale or in somewhat schematic form, and some details of conventionalelements may not be shown in the interest of clarity and conciseness. Itis to be fully recognized that the different teachings of theembodiments discussed below may be employed separately or in anysuitable combination to produce the desired results.

Accordingly, the drawings and descriptions are to be regarded asillustrative in nature, and not as restrictive. Furthermore, theterminology and phraseology used herein is solely used for descriptivepurposes and should not be construed as limiting in scope. Language suchas “including,” “comprising,” “having,” “containing,” or “involving,”and variations thereof, is intended to be broad and encompass thesubject matter listed thereafter, equivalents, and additional subjectmatter not recited, and is not intended to exclude other additives,components, integers or steps. Likewise, the term “comprising” isconsidered synonymous with the terms “including” or “containing” forapplicable legal purposes.

All numerical values in this disclosure are understood as being modifiedby “about”. All singular forms of elements, or any other componentsdescribed herein including (without limitations) components of theapparatus are understood to include plural forms thereof.

An embodiment of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings of which:

FIG. 1 is a cross-sectional view through an assembly according to anembodiment of the present invention;

FIG. 2 is a cross-sectional view through the assembly of FIG. 1following morphing of the sleeve member; and

FIGS. 3 a-3 c are schematic illustrations of a sequence for setting twosleeve members in an open borehole; FIG. 3 a is a cross-sectional viewof a liner provided with two sleeve members; FIG. 3 b shows the liner inthe borehole of FIG. 3 a with an activation fluid delivery tool insertedtherein; and FIG. 3 c is a cross-sectional view of the liner of FIGS. 3a and 3 b with morphed sleeves and a relaxed torsion spring, in use.

Reference is initially made to FIG. 1 of the drawings which illustratesan assembly, generally indicated by reference numeral 10, including atubular body 12, sleeve member 14, chamber 16, port 18 and torsionspring, generally indicated by reference numeral 20, according to anembodiment of the present invention.

Tubular body 12 is a cylindrical tubular section having at a first end22, a first connector (not shown) and at an opposite end 26, a secondconnector (not shown) for connecting the body 12 into a tubing stringsuch as casing, liner or production tubing that is intended to bepermanently set or completed in a well bore. Body 12 includes athroughbore 30 which is co-linear with the throughbore of the string.The string may be a drill pipe or any other tubular string designed tobe run in a well bore.

A port 18 is provided through the side wall 34 of the body 12 to providea fluid passageway between the throughbore 30 and the outer surface 36of the body 12. While only a single port 18 is shown, it will beappreciated that a set of ports may be provided. These ports may beequidistantly spaced around the circumference of the body 12 and/or bearranged along the body between the first end 22 and the second end 26to access the chamber 16.

In an embodiment, at the port 18 there is located a check valve 54. Thecheck valve 54 is a one-way valve which only permits fluid to pass fromthe throughbore 30 into the chamber 16. The check valve 54 can be madeto close when the pressure within the chamber 16 reaches a predeterminedlevel, this being defined as the morphed pressure value. Thus, when thepressure in the sleeve 14 reaches the morphed pressure value, the valve54 will close. Also arranged at the port 18 is a rupture disc 56. Therupture disc 56 is rated to a desired pressure at which fluid access tothe chamber is desired. In this way, the rupture disc 56 can be used tocontrol when the setting of the sleeve 14 is to begin. The disc 56 canbe operated by increasing pressure in the throughbore 30 with thepressure to rupture the disc being selected to be greater than the fluidpressure required to activate any other tools or functions in the wellbore.

Tubular body 12 is located coaxially within a sleeve member 14. Sleevemember 14 is a steel cylinder being formed from typically 316L or Alloy28 grade steel but could be any other suitable grade of steel or anyother metal material or any other suitable material which undergoeselastic and plastic deformation. Ideally the material exhibits highductility i.e. high strain before failure. The sleeve member 14 isappreciably thin-walled of lower gauge than the tubing body 12 and ispreferably formed from a softer and/or more ductile material than thatused for the tool body 12. The sleeve member 14 may be provided with anon-uniform outer surface 40 such as ribbed, grooved or other keyedsurface in order to increase the effectiveness of the seal created bythe sleeve member 14 when secured within another casing section orborehole.

An elastomer or other deformable material may be bonded to the outersurface 40 of the sleeve 14; this may be as a single coating but ispreferably a multiple of bands with gaps therebetween. The bands orcoating may have a profile or profiles machined into them. The elastomerbands may be spaced such that when the sleeve 14 is being morphed thebands will contact the inside surface 24 of the larger diameterstructure (casing 28 or open borehole 80) first. The sleeve member 14will continue to expand outwards into the spaces between the bands,thereby causing a corrugated effect on the sleeve member 14. Thesecorrugations provide a great advantage in that they increase thestiffness of the sleeve member 14, increase its resistance to collapseforces and also improves annular sealing.

Sleeve member 14 which surrounds the tubular body 12 is affixed theretovia welded or clamped connections 42, 44, respectively. Such attachments42, 44 are pressure-tight connectors. An O-ring seal (not shown) mayalso be provided between the inner surface 46 of the sleeve member 14and the outer surface 36 of the tubular body 12 to act as a secondaryseal or back-up to the seal provided by the welded connections. In anembodiment of the present invention, the first attachment means 42 isprovided by a mechanical clamp to fix the first end 48 of sleeve member14 to the tubular body 12. The second end 50 of the sleeve member 14 isconnected to the outer surface 36 of the tubular body 12 via a slidingseal arrangement. In this way, the second end 50 of the sleeve member 14can move longitudinally along the outer surface 36 of the tubular body12 while maintaining a seal between the surfaces to hold pressure withinthe chamber 16. This sliding seal is arranged so that the second end 50of the sleeve member 14 is permitted to move towards the first end 48.Thus when the sleeve member 14 is caused to move in a radially outwarddirection, during morphing, the sleeve contracts which causessimultaneous movement of the sliding seal. This has the advantage inreducing thinning of the material of the sleeve 14 by the radial outwardexpansion.

The attachments 42, 44 together with the inner surface 46 of the sleevemember 14 and the outward surface 36 of the body 12 define the chamber16. The port 18 is arranged to access the chamber 16 and permit fluidcommunication between the through-bore 30 and the chamber 16.

Located within the chamber 16, is a torsion spring 20. Torsion spring 20comprises a helically wound wire. Torsion spring 20, as shown in theembodiment in FIG. 1, has a circular cross-section 52 but may preferablyhave a square or rectangular cross-section so as to provide a smoothcontact between the outer surface 58 of the spring 20 and the innersurface 46 of the sleeve 14.

Torsion spring 20 is as known in the art of helically wound coiledspring design in which energy is stored within the spring 20 by beingtightly wound and held in compression. In the embodiment shown in FIG.1, torsion spring 20 is in compression. Naturally, the torsion spring 20wishes to relax and in doing so, will wish to unwind and thus provide aradially outward force from the body 12 against the inner surface 46 ofthe sleeve member 14. Thus, once constructed, the assembly 10 will havethe torsion spring 20 held in compression within the chamber 16. In theembodiment shown, there is a single torsion spring 20 extending from afirst end 48 of the sleeve member to a second end 50 of the sleevemember along the entire length of the chamber 16. Alternatively, theremay be a number of separate torsion springs arranged along the length ofthe chamber 16. In this arrangement, the centre-most torsion spring mayhave a higher compressibility factor so that it exerts a stronger radialforce against the inner surface 46 of the sleeve member 14 thus causingexpansion at the centre point of the sleeve member 14 ahead of the outerends 48, 50 of the sleeve member. This will assist in preventinghydraulic lock during morphing of the sleeve member 14.

The torsion spring may be held against the outer surface 36 of thetubular body 12, held against the inner surface 46 of the sleeve member14 or preferably let free within the chamber 16 and not be directlyattached to any part thereof.

Thus, the assembly 10 is constructed by taking a tubular body 12 andlocating a sleeve member 14 thereon. A first end 48 of the sleeve member14 is attached to the tubular body via the attachment 42. The torsionspring 20 is then compressed under tension by tightening the spring toreduce its diameter so that it fits within the inner diameter of thesleeve member 14. Once located in the sleeve, the second end 50 of thesleeve member is also attached to the tubular body, via attachment 44.The diameter of the sleeve member 14 will have been selected to matchthe inner diameter of the casing 28 into which the assembly 10 isintended for use. Likewise, the torsion spring 20 will have beenselected so that its relaxed diameter i.e. the diameter in which thespring takes up when entirely unwound and unbounded is selected to beless than the inner diameter of the casing 28 and preferably of adiameter less than the intended diameter for the morphed sleeve 14. Thiswill be described hereinafter with reference to the morphed sleeve.Assembly 10 is then connected into a string as is known in the art andrun into the wellbore 60. The assembly 10 is run into a position where abarrier is required and in the embodiment shown in FIG. 1, this isinside casing 28. As casing 28 comes in standard sizes of diameters thenthe assembly 10 of the present invention can also be formed in standardsizes selected for the diameter of the casing in which it will form abarrier.

When the assembly 10 is in position in the casing 28, pressure in thethrough-bore 30 is increased. This is typically fluid pressure deliveredfrom a pump at surface with a plug or stop located within thethrough-bore 30 at a position below the assembly 10 in the string.Pressure in the through-bore 30 thus increases to a point where the disc56 ruptures and allows fluid under pressure to pass through the checkvalve 54 at the port 18. As detailed previously, multiple ports 18 maybe located upon the tubular body 12 to increase the rate of fluidpressure entering the chamber 16. The torsion spring 20 ispreferentially wound to provide a spacing between the individual coilsof the helix so that as the fluid enters chamber 16, it will passthrough the torsion spring 20 unimpeded and act against the innersurface 46 of the sleeve member 14. As the chamber 16 is cylindrical innature and the material of the sleeve member 14 is more elastic thanthat of the tubular body 12, as pressure increases in the chamber 16,the sleeve member 14 will be forced radially outwardly from the tubularbody across the annulus 62 between the outer surface 36 of the tubularbody 12 and the inner surface 24 of the casing 28. This expansion of thesleeve member 14 by fluid pressure is assisted by the torsion spring 20also expanding as it unwinds in the greater space being made availableas the chamber 16 increases in volume. During unwinding of the torsionspring 20, the spring 20 will exert a radial force on the inner surface46 of the sleeve member 14.

Fluid pressure will continue to enter through port 18 until the sleevemember 14 contacts the inner surface 24 of the casing 28 and effectivelymorphs the material of the sleeve member 14 against the inner surface24. This morphing creates a metal-to-metal seal between the sleevemember 14 and the casing 28. This process is known and operates byelastically and then plastically deforming the sleeve member 14. Oncontact with the casing 28, the casing 28 may also elastically deformunder fluid pressure. At a morphed fluid pressure value, the check valve54 closes therefore sealing the chamber 16. At this pressure value, thesealed chamber and in particular, the sleeve member 14 will wish torelax slightly. This relaxation will cause the elastically deformedcasing 28 to also contract back to its original diameter. This movementimproves the metal-to-metal seal between the sleeve 14 and the casing28. The seal between the assembly 10 and the casing 28 thus forms abarrier in the wellbore 60 so that fluid flow through the annulus 62 isprevented. Indeed, a loss of fluid flow through the annulus 62 can beconsidered as the point at which an effective barrier seal has been madeby the assembly 10.

During morphing of the sleeve member 14, the torsion spring 20 hasunwound to a relaxed position as shown in FIG. 2. The spring 20 has nowincreased in diameter and is located just within the inner surface 46 ofthe sleeve 14. It may contact the sleeve 14 but the torsion spring 20 isdesigned such that it provides no radial force against the inner wall 46of the sleeve 14 when in the relaxed position. The torsion spring 20thus merely acts as a metal frame located within the chamber 16. Duringthe morphing process, the second end 50 of the sleeve member 14 willhave moved towards the first end 48 of the sleeve member 14 due to thelongitudinal contraction of the sleeve member during radial expansion.The spring 20 may also have reduced in length within the chamber 16. Thehelical arrangement of the torsion spring 20 can reduce in lengthwithout affecting the diameter it takes up within the chamber 16.

The frame created by the torsion spring 20 in its relaxed positionprovides a support to the sleeve member 14 in the event that there isany potential collapse to the sleeve member 14. In such morphed sleevearrangements, collapse can occur from a difference in the differentialpressure between the pressure in chamber 16 and that in the annulus 62above or below the assembly 10. Essentially, once morphed, the spring 20is there to prevent the morphed sleeve 14 from changing shape andgetting to its first buckling mode (essentially going from a round to aheart shape). By preventing such a change in shape occurring, thebarrier will retain its sealing ability against the casing 28. Thus, byincorporating a torsion spring 20 into the design, this allows for lowermorph pressures to be used and accommodate a larger pressuredifferential across the barrier.

Reference will now be made to FIGS. 3 a-3 c of the drawings whichprovides an illustration of a further method for setting a sleeve withina well bore according to an embodiment of the present invention. Likeparts to those in the earlier Figures have been given the same referencenumerals to aid clarity.

In use, the assembly 10 is conveyed into the borehole by any suitablemeans, such as incorporating the assembly 10 into a casing or linerstring 76 or on an end of a drill pipe and running the string into thewellbore 78 until it reaches the location within the open borehole 80 atwhich operation of the assembly 10 is intended. This location isnormally within the borehole at a position where the sleeve 14 is to beexpanded in order to, for example, isolate the section of borehole 80 blocated above the sleeve 14 from that below 80 d in order to provide anisolation barrier between the zones 80 b, 80 d. Additionally a furtherassembly 10 b can be run on the same string 76 so that zonal isolationcan be performed in a zone 80 b in order that an injection, frac′ing orstimulation operation can be performed on the formation 80 b locatedbetween the two sleeves 14, 14 b. This is as illustrated in FIG. 3B.

Each sleeve 14, 14 b can be set by increasing the pump pressure in thethroughbore 30 to a predetermined value which ruptures the disc 56giving fluid access to the chamber 16. Fluid entering the chamber 16increases in internal volume of the chamber 16, creating a pressure onthe inner wall 46 sufficient to cause the sleeve 14 to move radiallyaway from the body 12 by elastic expansion, contact the surface 82 ofthe borehole and morph to the surface 82 by plastic deformation.

Fluid may be pumped into the chamber 16 at any desired pressure as thecheck valve 54 can be set to allow a calculated volume of fluid which issufficient to morph the sleeve to enter the chamber before closing. Whenclosed, the check-valve will trap any fluid remaining in the chamber 16.

Additionally, by locating a plug at any desired position in the string,such as the bottom of the string, fluid can be pumped from surface orfrom a tool located in the string to morph any desired number ofsleeves, between the surface/tool and the plug, at the same time.

On run-in the torsion spring 20 is in a compressed state being held intension. As the sleeve 14 is moved radially outwards, the second end 50of the sleeve 14 will move towards the first end 42 of the sleeve 14.The sliding seal maintains contact on the liner 76 to ensure the chamber16 remains sealed. Movement of the sleeve 14 radially outwardly expandsthe volume of the chamber and hence the torsion spring 20. As thetorsion spring 20 unwinds it will exert a radial force upon the sleeve14 and support the expansion of the sleeve. Note that this movement ofthe torsion spring 20 does not require separate intervention and occursautomatically on radial movement of the sleeve 14 due to morphing of thesleeve 14.

The sleeve 14 will have taken up a fixed shape under plastic deformationwith an inner surface 46 matching the profile of the surface 82 of theborehole 80, and an outer surface also matching the profile of thesurface 82 to provide a seal which effectively isolates the annulus 84of the borehole 80 above the sleeve 14 from the annulus 86 below thesleeve 14. If two sleeves 14, 14 b are set together then zonal isolationcan be achieved for the annulus 84 between the sleeves 14, 14 b. At thesame time the sleeves 14,14 a have effectively centered, secured andanchored the tubing string 76 to the borehole 80. When the sleeves 14,14 b are morphed, the respective torsion springs 20 will have entirelyunwound to their relaxed state creating a frame within the sleeves 14,14 b. The torsion springs 20 do not exert any radial force on themorphed sleeves 14, 14 b and support to the sleeves 14, 14 b againstcollapse in the morphed configuration.

An alternative method of achieving morphing of the sleeve 14 is shown inFIG. 3B. This method uses an activation fluid delivery tool 88. Once thestring 76 reaches its intended location, tool 88 can be run into thestring 76 from surface by means of a coiled tubing 90 or other suitablemethod. The tool 88 is provided with upper and lower seal means 92,which are operable to radially expand to seal against the inner surface94 of the body 12 at a pair of spaced apart locations in order toisolate an internal portion of body 12 located between the seals 92; itshould be noted that said isolated portion includes the fluid port 18.Tool 88 is also provided with an aperture 96 in fluid communication withthe interior of the string 76.

To operate the tool 88, seal means 92 are actuated from the surface toisolate the portion of the tool body 12. Activation fluid is then pumpedunder pressure through the coiled tubing such that the pressurised fluidflows through tool aperture 96 and then via port 18 into chamber 16 andacts on the sleeve members 14,14 b in the same manner as describedhereinbefore. Use of such a tool allows setting of selective assemblies10 in a well bore.

A detailed description of the operation of such a fluid delivery tool 88is described in GB2398312 in relation to the packer tool 112 shown inFIG. 27 of that patent with suitable modifications thereto, where theseal means 92 could be provided by suitably modified seal assemblies214, 215 of GB2398312, the disclosure of which is incorporated herein byreference. The entire disclosure of GB2398312 is incorporated herein byreference.

Using either pumping method, the increase in pressure of fluid causesthe sleeve 14 to move radially outwardly and seal against a portion ofthe inner circumference of the borehole 80 and the torsion spring 20 torelax and form a frame to support the sleeve 14 in the event of collapsein the morphed position. The pressure within the chamber 16 continues toincrease such that the sleeve 14 initially experiences elastic expansionfollowed by plastic deformation. The sleeve 14 expands radiallyoutwardly beyond its yield point, undergoing plastic deformation untilthe sleeve 14 morphs against the surface 82 of the borehole 80 as shownin FIG. 3C. Accordingly, the sleeve 14 has been plastically deformed andmorphed by pressure from the chamber contents without any mechanicalexpansion means being required. Note that the springs 20 support thesleeve during morphing of the sleeve but do not provide any support oncemorphing is complete unless a pressure differential is created acrossthe sleeve 14 which would wish to cause the sleeve 14 to collapse. Thespring 20 then acts as a support frame to prevent collapse of the sleeve14 and maintain the seal.

The principle advantage of the present invention is that it provides anassembly for creating an isolation barrier in a well bore in which atorsion spring is used to create a supporting frame for the morphedsleeve in the event of collapsing of the sleeve.

A further advantage of the present invention is that it provides amethod for setting a sleeve in a well bore in which support of thesleeve is achieved without additional intervention by using movement ofthe sleeve during the morphing process to provide for expansion of thespring.

It will be apparent to those skilled in the art that modifications maybe made to the invention herein described without departing from thescope thereof. For example, while a single torsion spring is described,multiple torsion springs may be used to create the frame.

1. An assembly, comprising: a tubular body arranged to be run in andsecured within a larger diameter generally cylindrical structure; asleeve member positioned on the exterior of the tubular body, to createa chamber therebetween; the tubular body including a port to permit theflow of fluid into the chamber to cause the sleeve member to moveoutwardly and morph against an inner surface of the larger diameterstructure; and characterised in that: at least one torsion spring islocated within the chamber; the torsion spring relaxing as the sleevemember is moved outwardly by fluid pressure to provide a frame withinthe chamber when the sleeve member is morphed against the inner surfaceof the larger diameter structure.
 2. An assembly according to claim 1wherein, the torsion spring is a helically coiled spring which unwindsas it relaxes.
 3. An assembly according to claim 1, the torsion springhas a relaxed diameter less than a diameter of the larger diameterstructure.
 4. An assembly according to claim 3 wherein, the torsionspring has a relaxed diameter less than a diameter of the morphedsleeve.
 5. An assembly according to claim 1 wherein, the torsion springhas a rectangular cross-section.
 6. An assembly according to claim 1wherein, the torsion spring has a square cross-section.
 7. An assemblyaccording to claim 1 wherein, the sleeve member has a first end which isaffixed and sealed to the tubular body and a second end which includes asliding seal to permit longitudinal movement of the second end over thetubular body.
 8. An assembly according to claim 1 wherein the largediameter structure is selected from a group comprising: an open holeborehole, a borehole lined with a casing or liner string, a boreholelined with a casing or liner string which is cemented in place downhole;a pipeline within which another smaller diameter tubular sectionrequires to be secured or a pipeline within which another smallerdiameter tubular section requires to be centralised.
 9. An assemblyaccording to claim 1 wherein the tubular body is located coaxiallywithin the sleeve and is part of a tubular string used within awellbore.
 10. An assembly according to claim 1 wherein there is aplurality of ports arranged through the tubular body.
 11. An assemblyaccording to claim 1 wherein the port includes a barrier.
 12. Anassembly according to claim 11 wherein the barrier is a rupture discwhich allows fluid to flow through the port at a predetermined fluidpressure.
 13. An assembly according to claim 11 wherein the barrierincludes a valve.
 14. An assembly according to claim 13 wherein thevalve is a one-way check valve.
 15. A method of setting a morphed sleevein a well bore, comprising the steps: (a) locating a sleeve member onthe exterior of a tubular body and sealing it thereto to create achamber therebetween, (b) locating a torsion spring in the chamber; (c)running the tubular body on a tubular member into a wellbore andpositioning the sleeve member at a desired location within a largerdiameter structure; (d) pumping fluid through the tubular member andthrough a port in the tubular body to access the chamber; (e) causingthe sleeve member to move radially outwardly and morph against an innersurface of the larger diameter structure; (f) allowing the torsionspring to relax and exert a radial force on the sleeve member as thesleeve member is moved radially outwardly towards the inner surface ofthe larger diameter structure; and (g) creating a frame from the relaxedtorsion spring to prevent collapse of the morphed sleeve member.
 16. Amethod of setting a morphed sleeve in a well bore according to claim 15wherein, the method includes the step of selecting a torsion springhaving a relaxed diameter less than a diameter of the larger diameterstructure.
 17. A method of setting a morphed sleeve in a well boreaccording to claim 16 wherein, the method includes the step of selectinga torsion spring having a relaxed diameter less than a calculateddiameter of the morphed sleeve.
 18. A method of setting a morphed sleevein a well bore according to any claim 15 wherein step (d) includes thestep of pumping fluid through the tubular member and through multipleports in the tubular body to access the chamber.
 19. A method of settinga morphed sleeve in a well bore according to claim 15 wherein the methodincludes the step of rupturing a disc at a valve in the port to allowfluid to enter the chamber when the pressure reaches a desired value.20. A method of setting a morphed sleeve in a well bore according toclaim 15 wherein the method includes the steps of running in anactivation fluid delivery tool, creating a temporary seal above andbelow the port and injecting fluid from the tool into the chamber viathe port.